Move Your Japan eSIM Safely: A No-Service-Loss Checklist for a New Phone

2026年9月9日

Moving Your Japan eSIM to a New Phone: The Safe Order That Keeps You Connected

Do not erase, trade in, or reset your old phone first. Connect the new phone to Wi-Fi, confirm that both the device and your Japanese carrier support eSIM transfer, move or reissue the eSIM, and test calls, SMS, and mobile data before touching the old device.

For many iPhone-to-iPhone moves—and some Android-to-Android moves—the transfer can happen in the phone’s settings. If that option does not appear, you normally need an eSIM reissue through your carrier rather than a reusable QR code.

This guide is for residents, students, workers, and longer-term visitors who want to keep a Japanese mobile number while changing phones.

The essentials

Keep the old phone powered on and connected until the new line works.
Prepare reliable Wi-Fi and your carrier account login.
Check the new phone’s eSIM support, network compatibility, and SIM-lock status.
Treat the old activation QR code as single-use unless the provider explicitly says otherwise.
Test calls, SMS, and mobile data before resetting the old phone.

TOC

First identify what you are actually transferring

Your phone number belongs to the carrier account, while the eSIM profile is the digital credential installed on one device. Copying photos and apps does not necessarily move that credential.

Three different operations are often confused:

Data transfer: copies apps, photos, contacts, messages, and settings.
eSIM transfer: moves an active line directly between supported devices.
eSIM reissue: the carrier creates a new profile for the replacement phone.

In Japanese support pages, look for these terms:

kishu henkō (機種変更): changing your phone or device
eSIM tensō (eSIM転送): eSIM transfer
eSIM sai-hakkō (eSIM再発行): eSIM reissue
kai-sen kirikae (回線切り替え): switching or activating the line
kai-tsū (開通): service activation

The distinction matters because restoring a complete cloud backup can leave the new phone looking ready while it still has no working mobile line.

Before starting: complete this checklist

The safest transfer begins before you open the new phone’s setup screen. A few checks prevent most service interruptions.

Check the replacement phone

Confirm that the new device:

supports eSIM;
supports the frequency bands used by your carrier in Japan;
is not locked to an incompatible carrier;
has current system software;
can connect to Wi-Fi; and
has enough battery for setup and activation.

A phone bought overseas may support eSIM but lack bands important for coverage in Japan. Carrier compatibility lists are therefore more useful than the word “eSIM” on the box.

On an iPhone, you can usually find the device identifier under Settings → General → About. Japanese carrier forms may ask for an EID, the identification number associated with the phone’s eSIM hardware.

Prepare access to the old line and account

Keep the old phone nearby, unlocked, and connected. You may need it to:

approve an on-device transfer;
receive an SMS verification code;
open an activation email;
sign in to the carrier’s account portal; or
display information required for a reissue.

Before starting, confirm that you know the login details for services such as My docomo, My au, My SoftBank, or the relevant low-cost carrier account.

If account verification depends on SMS sent to the line being moved, do not disable or erase that line prematurely.

Make a separate backup

Back up photos, contacts, authenticator apps, messaging history, and other important data. Check banking and payment apps separately: some require fresh device registration even when the app itself is restored.

An eSIM transfer does not automatically transfer every app credential.

ここがポイント: Keep the old device usable until the new phone can make a call, receive an SMS, and load a webpage with Wi-Fi turned off.

Choose the correct transfer route

Use direct device transfer when your exact carrier-and-phone combination supports it; otherwise use the carrier’s official reissue process. Do not improvise with an old QR code.

Route A: iPhone to iPhone

Apple’s eSIM Quick Transfer can move a phone number from a nearby iPhone without contacting the carrier separately, but only when the carrier supports the feature and the devices meet Apple’s requirements.

During setup, keep both iPhones nearby and follow the mobile-service prompts. If the new iPhone has already been set up, Apple also provides an option under Settings → Cellular/Mobile Data → Add eSIM, where a supported line may appear for transfer.

Japan’s major carriers do not all apply identical eligibility rules. For example:

NTT DOCOMO states that supported iPhone and iPad users can reissue an eSIM through device settings, although transfer between an iPhone and an iPad is not supported.
SoftBank offers eSIM Quick Transfer for eligible lines and devices. Its published requirements and supported procedures should be checked for the particular brand—SoftBank, Y!mobile, or LINEMO—and current software version.
Other carriers and budget brands may require their account portal, app, identity verification, or a newly issued activation profile.

If “Transfer from Nearby iPhone” does not appear, stop and check the carrier’s instructions. Its absence does not prove that the phone is faulty.

Route B: Android to Android

Android transfer support depends heavily on the carrier, phone manufacturer, software version, and where the devices were sold.

Google explains that supported Android phones can offer SIM transfer during initial setup or later under a path such as Settings → Network & internet → SIMs → Add SIM → Transfer SIM from another device. Automatic transfer generally requires both phones to have Android 12 or later, current Google Play services, and screen locks.

Those operating-system requirements are only one part of the check. The Japanese carrier must also support the transfer for that line and those devices.

SoftBank, for example, publishes a separate Android eSIM transfer guide and limits its supported transfer feature to specified devices. Unsupported phones must use another carrier procedure, such as an eSIM device-change application.

Route C: iPhone and Android in either direction

Cross-platform moves are less predictable. Even when a new Pixel or iPhone offers a transfer prompt, carrier support still determines whether the line can be activated that way.

If the prompt is missing or fails, use the carrier’s eSIM sai-hakkō process. This usually means signing in online, confirming the line and replacement device, completing any required verification, and downloading a new profile over Wi-Fi.

Do not delete the old profile merely to make the button appear.

Route D: a travel or data-only eSIM

A short-term travel eSIM is often managed by the provider rather than a Japanese mobile carrier. Its rules may be stricter:

some plans allow installation only once;
some can be reinstalled through the provider’s app;
some require support to reset or replace the profile;
some expire after activation or after a fixed validity period; and
data-only plans may not include a Japanese phone number or SMS.

Check the provider’s installation and replacement policy before resetting the old phone. A screenshot of the original QR code is not proof that it can be used again.

A safe transfer sequence

Activate first and erase last. This order gives you a working fallback if verification or provisioning fails.

1. Update and charge both phones

Install current system updates where practical, charge both devices, and connect the replacement phone to stable Wi-Fi. Keep the carrier account page available on another device if possible.

2. Transfer ordinary data

Use Apple Quick Start, Android’s setup process, or the manufacturer’s migration tool for apps and personal data. Remember that this stage may not activate the mobile line.

If the setup process offers an eSIM transfer and your carrier officially supports it, follow the prompts. Otherwise, finish the ordinary data migration without deleting anything from the old phone.

3. Transfer or reissue the eSIM

Use one of the following official routes:

the phone’s supported eSIM transfer screen;
the carrier’s website or account app;
an activation link or new QR code supplied by the carrier; or
carrier support or a shop when online verification is unavailable.

For an activation based on a QR code, display the code on another phone, tablet, or computer so the replacement phone can scan it. Follow the carrier’s order carefully: some procedures require kai-sen kirikae, or line switching, before the profile download.

4. Wait for activation to finish

The old phone may lose service as soon as the replacement profile becomes active. That is normally expected because one mobile line is generally not active on two ordinary handset profiles at once.

Do not repeatedly delete and reinstall profiles while the carrier system is processing the change. If the screen remains stuck, record the error message and check the carrier’s service-status and support pages.

5. Test the replacement phone

Turn off Wi-Fi and check all services you actually use:

open a webpage over mobile data;
make an outgoing call;
ask someone or another phone to call you;
send and receive SMS;
confirm the correct number appears in the phone’s SIM settings; and
test tethering if it is included in your plan.

Dual-SIM users should also set the correct default line for mobile data, voice calls, and messages. A successful activation can still look like a failure if the phone is trying to use the wrong line.

6. Only then reset the old phone

After testing, sign out of sensitive apps as required and follow the manufacturer’s erase procedure. If an erase screen asks whether to keep or delete an eSIM, read it carefully and confirm which device and profile it refers to.

SoftBank specifically warns users who are resetting an iPhone during migration to choose the option that preserves the eSIM when the line has not yet been safely moved.

Costs and documents depend on the carrier

Direct self-service transfer may be free, but assisted reissue or shop procedures can cost money. The amount and available channel depend on the carrier, brand, contract type, and reason for the change.

As of August 22, 2026:

DOCOMO’s English eSIM page says a handling fee of ¥4,950 including tax may apply to procedures at a DOCOMO Shop or Call Center.
SoftBank states that eligible self-service iPhone or Android eSIM transfers do not incur an administrative fee, while other reissue or device-change procedures can follow different fee rules.
au provides online activation and reissue instructions, but the required sequence differs by device and how the replacement phone was obtained.

These examples should not be treated as a universal Japan-wide price list. Check the page for your exact carrier brand immediately before starting.

If online verification fails and you must visit a shop, the carrier may request items such as:

the replacement phone;
accepted identity documents;
account or contract information;
the old device, if available; and
a payment method.

Foreign residents should check whether the carrier requires a residence card, passport, or another specific form of identification for the requested procedure. Requirements can differ from those for opening a new contract.

Common mistakes that can cut off service

Most avoidable failures come from erasing the only working profile or assuming that all eSIMs transfer in the same way.

Reusing the first QR code

Many activation QR codes cannot simply be scanned a second time. Request a fresh profile through the provider’s official process unless its instructions clearly permit reuse.

Trading in the old phone too early

The old device may be needed for approval or SMS authentication. Complete and test the transfer before handing it to a shop, courier, employer, or buyer.

Assuming a backup contains the eSIM

A cloud or cable backup protects ordinary data but does not guarantee that an active carrier profile will be restored. Treat line activation as a separate task.

Starting without Wi-Fi

The new phone often needs internet access to download its eSIM profile. Do the transfer somewhere with reliable Wi-Fi rather than while travelling between locations.

Ignoring dual-SIM settings

The new eSIM may be active while mobile data remains assigned to another line. Check the default line and data-roaming settings for each SIM.

For a Japanese domestic plan, data roaming is normally not needed inside Japan. A foreign travel eSIM may instruct you to enable roaming because it connects through a partner network; follow that provider’s directions.

Changing phones while overseas

A Japanese carrier may require access to its domestic network, SMS verification, Japanese account details, or a supported online identity check. If you are outside Japan, confirm the procedure before disabling the old phone. Carrier support may need to provide an alternative.

What to do when the transfer fails

Preserve the old working setup and identify the failed stage before trying again. Random deletion makes recovery harder.

Work through these checks:

Confirm that the replacement phone has Wi-Fi access.
Restart both devices once.
Check for system and carrier-setting updates.
Confirm that the phone is unlocked and listed as compatible.
Check whether the line is still active on the old phone.
Read the carrier account page for a pending activation or reissue.
Contact the carrier with the exact error message, device models, and operating-system versions.

If neither phone has service, use Wi-Fi calling only if it was already configured and supported; otherwise contact the carrier through web chat, another telephone, or a shop. SoftBank’s English support page includes customer-support information and a search for shops with multilingual assistance. Other carriers may have more limited English support, so screenshots of Japanese error messages can help at the counter.

The final five-minute check

A transfer is finished only after the replacement phone works away from Wi-Fi. Before erasing the previous device, verify:

mobile data loads a webpage;
incoming and outgoing calls work;
SMS arrives on the new phone;
the intended line is selected for data and calls;
banking and authentication apps are accessible; and
the carrier account shows the expected device or eSIM status.

The most important practical rule is simple: keep the old phone intact until every essential function passes on the new one. If your carrier does not show a supported direct-transfer route, request an official eSIM reissue instead of deleting profiles or repeatedly scanning an old code.

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